Multilateral well drilling and production, where separately spaced apart wells extend laterally from a common wellbore, have become increasingly important to the oil industry in recent years, both from the standpoint of new drilling operations, and from the standpoint of reworking existing wellbores. A multilateral well completion frequently improves production to a point that offsets the increased drilling and completion costs. This increased production from multilateral wells, where the lateral wells can be inclined or even horizontal, minimizes the number of production trees required on shore, and likewise minimizes the number of offshore platforms required to maintain a desired production rate. Further, other equipment costs such as casing, tubing, wellheads, bits, muds and other drilling items are reduced. Multilateral drilling also makes petroleum reservoirs in urban areas, permafrost zones, deep offshore waters and faulted reservoirs more accessible for economic recovery. Accordingly, the preferred drilling technique of the future, especially in the oil industry, is multilateral drilling.
However, if the oil industry is to continue to grow, cost reductions are necessary especially in the drilling and completing of multilateral wells. For example, the need to reduce the size and number of offshore platforms while simultaneously developing smaller and often discontinuous reservoirs, which can readily be accomplished with multilateral completions, is an important concern for the oil industry. Accordingly, an urgent need exists for new and improved methods and tools that reduce drilling and completion time required for multilateral wells.
Accordingly, it is an object of this invention to reduce the number and cost of wells required to economically develop oil and/or gas fields.
It is a more specific object of this invention to improve techniques and tools for drilling and completing multilateral wells which can produce oil from separate formation through a single vertical wellbore.
Another object is to drill and complete multilateral wells having full pressure integrity at lateral junctions.
Still, another object is to safely complete several separate reservoirs having different formation pressures from the same well.
Another specific object is to safely complete multiple high pressure reservoirs with a multilateral well.
Yet another object of this invention is to accelerate production and cash flow by reducing drilling and completion time.
Still, another object is to achieve simultaneous production and injection in the same reservoir in a single well.